Raoul tells us: "We spotted a fleet of camouflaged test mules on the autostrada. We knew they were BMWs because they were accompanied by a black 1-series with the sign 'Werkstestwagen' on the back; plus, all of the cars registered in Munich. I chased them while my girlfriend Clarismelda took pictures – and we gleefully felt like bad-ass paparazzi."

Don't be fooled by the appearance of a side gill on the right flank: this isn't a high-performance M4 variant. Though that car will come – packing a twin-turbo straight six engine with around 450bhp – this appears to be a more vanilla 4-series Convertible, sporting slightly peeling camo-tape. Note the single exhaust pipe rather than quad tailpipes, unlike the M3 mule we've seen testing in the USA.

BMW 4-series: the need-to-know

The 4-series Convertible will keep the folding hard-top design of the outgoing 3-series, unlike its soft-top Audi A5 rival. Why the name switch from 3 to 4? BMW wants to distinguish its coupes from their more mundane saloon sisters, as it has always done with the 5- and 6-series. As such, two-door variants of the current F30 3-series will be badged as 4-series, and the 1-series hatch will spawn a 2-series Coupe and Convertible line-up.

Look out for the 4-series Coupe in summer 2013, after a possible Geneva motor show unveiling. The origami-top Convertible will follow in early 2014. Prices are expected to rise more than is usual for 3-series derivatives, reflecting the more exclusive nature of the new moniker.